Search

Plant 1,4-naphthoquinones encompass a class of specialized metabolites known to mediate numerous plant-biotic interactions. This class of compounds also presents a remarkable case of convergent evolution. The 1,4-naphthoquinones are synthesized by species belonging to nearly 20 disparate orders spread throughout vascular plants, and their production occurs via one of four known biochemically distinct pathways. Recent developments from large-scale biology and genetic studies corroborate the existence of multiple pathways to synthesize plant 1,4-naphthoquinones and indicate that extraordinary events of metabolic innovation and links to respiratory and photosynthetic quinone metabolism probably contributed to their independent evolution. Moreover, because many 1,4-naphthoquinones are excreted into the rhizosphere and they are highly reactive in biological systems, plants that synthesize these compounds also needed to independently evolve strategies to deploy them and to resist their effects. In this review, we highlight new progress made in understanding specialized 1,4-naphthoquinone biosynthesis and trafficking with a focus on how these discoveries have shed light on the convergent evolution and diversification of this class of compounds in plants. We also discuss how emerging themes in metabolism-based herbicide resistance may provide clues to mechanisms plants employ to tolerate allelopathic 1,4-naphthoquinones., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

The properties of the human visual system are taken into account, along with the geometric aspects of an object, in a new surface remeshing algorithm and a new mesh simplification algorithm. Both algorithms have a preprocessing step and are followed by the remeshing or mesh simplification steps. The preprocessing step computes an importance map that indicates the visual masking potential of the visual patterns on the surface. The importance map is then used to guide the remeshing or mesh simplification algorithms. Two different methods are proposed for computing an importance map that indicates the masking potential of the visual patterns on the surface. The first one is based on the Sarnoff visual discrimination metric, and the second one is inspired by the visual masking tool available in the current JPEG2000 standard. Given an importance map, the surface remeshing algorithm automatically distributes few samples to surface regions with strong visual masking properties due to surface texturing, lighting variations, bump mapping, surface reflectance and inter-reflections. Similarly, the mesh simplification algorithm simplifies more aggressively where the light field of an object can hide more geometric artifacts.

Computer rendering is used to simulate the appearance of lighted objects for applications in architectural design, for animation and simulation in the entertainment industry, and for display and design in the automobile industry. Rapid advances in computer graphics technology suggest that in the near future it will be possible to produce photorealistic images of coated surfaces from scattering data. This could enable the identification of important parameters in the coatings manufacturing process that lead to desirable appearance, and to the design of virtual surfaces by visualizing prospective coating formulations once their optical properties are known. Here we report the results of our work to produce visually and radiometrically accurate renderings of selected appearance attributes of sample coated surfaces. It required changes in the rendering programs, which in general are not designed to accept high quality optical and material measurements, and changes in the optical measurement protocols. An outcome of this research is that some current ASTM standards can be replaced or enhanced by computer based standards of appearance.

Using a low-compliance pneumohydraulic infusion system, we mapped the entire esophagus of nine volunteers with no history of esophageal disease, centimeter by centimeter, to see if there was pressure symmetry throughout the esophagus during 5 mL wet swallows. We found that esophageal length varied from 21-25 cm. The esophageal low-pressure zone (LPZ) varies in distance from the upper esophageal sphincter (UES) (4-8 cm). The length of this LPZ is 2-3 cm in most subjects but low pressures (<50 mmHg) may occur for longer intervals in some. The amplitudes of most paired swallows were within 10 mmHg of each other, and in only 10% of swallows was the pressure difference more than 15 mmHg. We conclude that there is radial pressure symmetry throughout the normal esophagus. The LPZ coincides closely to the 50-50 point where the percentage of striated and smooth muscle distribution in the circular and longitudinal muscles is equal.

Objective: To determine the practice recommendations of Program Directors of infectious disease training programs with regard to infection prophylaxis for patients with prosthetic orthopedic devices who undergo gastrointestinal procedures., Methods: We surveyed Program Directors of infectious disease training programs to determine what they recommend when asked about antibiotic prophylaxis for patients with orthopedic prostheses who undergo gastrointestinal procedures., Results: More than 50% of the respondents agreed that prophylaxis is not indicated at any time for these procedures, although there was an almost even split when confronted with colonoscopy and polypectomy within 6 months of prosthesis insertion., Conclusions: Most Program Directors agree with the recommendations of the American Society for Gastrointestinal Endoscopy and do not recommend prophylactic antibiotics for these patients. If antibiotics are chosen, they should be the same ones that are recommended for infectious endocarditis by The American Heart Association.

Hyperbaric oxygen therapy is an important adjunct in the management of respiratory injuries secondary to smoke inhalation, especially when injury is complicated by inhalation of a toxic chemical such as carbon monoxide or cyanide. For carbon monoxide poisoning, such therapy has become a standard of practice. As more information becomes available concerning the ability of hyperbaric oxygen to reduce reperfusion injuries, we anticipate that this therapy will become a standard of practice for managing smoke inhalation injuries and cyanide poisoning as well.

A Forum for Our Readers Forum is intended to provide a sounding board for our readers. Perhaps you have a special way to treat a common medical problem, or you may want to air your views on a controversial topic. You may object to an article that we have published, or you may want to support one. You may have a new trend to report, identified through an interesting case or a series of patients. Whatever your ideas, we invite you to send them to us. Illustrative figures are welcomed. Address correspondence to Forum, THE PHYSICIAN AND SPORTSMEDICINE, 4530 W 77th St, Minneapolis, MN 55435.

To determine if atropine alone, gastric distension alone, or atropine plus gastric distension affected serum gastrin levels, we obtained serum gastrins on 45 consecutive patients who were randomized into two groups. Group 1 (27 patients) was premedicated with meperidine alone, 1.5 mg/kg I.M. Group 2 received atropine 0.6 mg I.M. in addition to meperidine. Blood samples were drawn: 1) before premedication, 2) 30 minutes after premedication, and 3) immediately after endoscopy. We found: 1) no statistical difference between mean basal gastrin levels for groups 1 and 2, 2) no change in basal serum gastrin levels after premedications in either group, and 3) that endoscopy caused no significant increase in mean serum gastrin levels. We conclude that endoscopy does not lead to a significant elevation of basal serum gastrin in patients premedicated with meperidine or meperidine and atropine.

An oral glucose and electrolyte solution (glucose 120 mmole/liter, Na 100 mEq/liter K 10 mEq/liter, Cl 70 mEq/liter, HCO3 40mEq/liter) was used successfully in a patient with the short bowel syndrome. We believe this solution reversed fluid and electrolyte losses and was responsible for her clinical improvement.

Normal persons often note chest or back pain during rapid ingestion of cold liquids, commonly believed to result from cold-induced "spasm" of esophageal muscle. We studied the effects of swallowing cold liquids on esophageal function in five normal subjects, aged 20 to 44 years, by comparing their response to cold ice cream (-5 degrees C) and room temperature ice cream mix (20 degrees C). Decreased peristaltic amplitude was seen during cold ice cream ingestion, primarily in the midesophagus. When seven subjects rapidly ingested ice cream until chest pain was produced and maintained for at least 60 s, complete absence of motor activity in the distal esophagus occurred, with slow return to normal during the ensuing five minutes. Our studies indicate that ingestion of cold liquids significantly depresses peristaltic amplitudes and frequency of peristalsis in normal persons, and pain is associated with complete absence of motor activity in the body of the esophagus, rather than esophageal "spasm" as commonly believed.

The peristaltic response of the normal human esophagus to 10 repeated water swallows separated by varying time intervals (5, 10, 15, 20, and 30 s) between swallows was studied. Pressures measured during the shorter time intervals were of lower amplitude than those at 30-s swallowing intervals throughout the esophagus, with the distal esophagus showing the greatest effect. Frequency of peristalsis was decreased throughout the esophagus with rapid swallowing, especially distally at the 5- and 10-s time intervals. There was no significant change in wave velocity or duration at these time intervals. These data suggest that there is a refractory period in the distal (smooth muscle) esophagus. A series of paired swallows separated by 5 s resulted in a significant decrease in amplitude of the first swallow, and this was more marked in the distal esophagus. These data indicate that there is an inhibition of the progression of peristalsis by a subsequent swallow, probably through a neural mechanism. These studies show that repeated liquid swallows may effect peristalsis by two mechanisms: refractoriness of esophageal smooth muscle and a neural inhibitory discharge.

Ninety-eight directors of infectious disease training programs responded to a questionnaire about bacterial endocarditis prophylaxis for susceptible patients during colonoscopy. Although 54% recommended a penicillin and an aminoglycoside, antibiotics commonly used to protect against the enterococcus, there are no published data to support the use of prophylaxis. Most directors of gastrointestinal training programs do not routinely use antibiotic prophylaxis during colonoscopy. If antibiotics are chosen, they should include a penicillin and an aminoglycoside or vancomycin (alone or with aminoglycoside) at the dosage schedule suggested by the American Heart Association Committee.

The authors report the first known case of atlanto-axial subluxation in Reiter arthritis. The type of analysis, including radiographic and laboratory examinations, required for a diagnosis of atypical Reiter disease is an important feature of the case.

We describe a 47-year-old male with chronic calcific pancreatitis who had a four-year history of occult gastrointestinal bleeding with three prior hospitalizations. At endoscopy on the fourth admission, hemobilia was identified. Arteriography showed a 3-cm-diameter dye blush in the head of the pancreas. A retention cyst had eroded into an adjacent artery, causing bleeding. A stone at the ampulla of Vater apparently served as a ball valve to prevent massive hemorrhage. We discuss the pathogenesis of hemobilia in chronic pancreatitis and suggested therapy.

Current state of the art methods for esophageal manometry may be performed with either a nonperfused probe with intraluminal transducers or a perfused catheter system. The perfusate should be driven by a low compliance pump through catheters 0.8 mm. in diameter. The upper esophageal sphincter pressure profile is asymmetrical, with higher pressures in the anterior and posterior directions than laterally. The lower esophageal sphincter pressures are higher in the left and left posterior directions. There is symmetry of peristaltic pressures in the body of the esophagus. The discussion of the physiology of swallowing includes the "on" response and the "off" and "duration" response. The lower esophageal sphincter is normally in a state of constant contraction and is relaxed following stimulation of the vagus nerve. The mechanisms of the control of the lower esophageal sphincter remain to be fully demonstrated.

A double blind study of 111 consecutive elective upper gastrointestinal endoscopies performed with a flexible fiberoptic esophagogastroduodenoscope was made to determine the efficacy of topical pharyngeal anesthesia with lidocaine as an adjunct to intramuscular meperidine, intramuscular atropine, and intravenous diazepam. Patients who received lidocaine rated the over-all endoscopy and passage of the endoscope significantly easier than did those receiving placebo. The endoscopist found that patients who received lidocaine tolerated endoscopy significantly better, although gagging was not affected.

We studied the esophageal musculature of 11 cadavers to assess the distribution of striated and smooth muscle. The lower 54-62% of the esophagus was found to be exclusively smooth muscle, the proximal 4.1-5.6% to be exclusively striated, and the remainder to be mixed. The area in which striated and smooth muscle portions were approximately equal, the 50/50 point, was found to be 4.7 +/- 0.6 cm from the proximal portion of the cricopharyngeus muscle. This point corresponds to the previously described physiologic low pressure zone in the proximal esophagus.

Current methods to evaluate patients with esophageal disease include barium swallow with fluoroscopy, which is useful in demonstrating structural defects. Disordered motility is better evaluated with a cine-esophagram. Recent application of radioisotopes has been useful in evaluation of esophageal reflux and the post-treatment of achalasia. Esophageal motility studies may evaluate lower esophageal sphincter and upper esophageal sphincter pressures and the response of the body of the esophagus to series of swallows. Since there is no "gold standard" for the evaluation of reflux esophagitis, some of the tests designed to evaluate reflux and the patient's reaction to acid in the esophagus include the acid infusion test, the standard acid reflux test, the acid clearance test, and 24-hour pH monitoring. Endoscopy with either the flexible or the rigid instrument is important for the diagnosis of obstruction or esophagitis and allows direct visualization of the esophagus. The treatment of reflux esophagitis is discussed. The differential diagnosis of dysphagia may include achalasia, diffuse esophageal spasm, and mechanical obstruction of the esophagus due to rings, webs, strictures, and benign or malignant tumors. The evaluation of dysphagia should include radiologic as well as endoscopic evaluation. Treatment of obstruction varies according to the nature of the lesion. The Mallory-Weiss syndrome or bleeding from the mucosal tears of the gastroesophageal junction and Boerhaave's syndrome, spontaneous esophageal perforation, are two disorders associated with vomiting. The Mallory-Weiss syndrome usually resolves without specific therapy, but a high index of suspicion is required for patients with chest pain after vomiting, as spontaneous perforation necessitates immediate surgery. Most diverticula need no treatment, but the Zenker diverticulum, if symptomatic, should probably be surgically repaired.

Within a few hours after being administered to the rhesus monkey (Macaca mulatta), Hysterothylacium type MB larvae penetrated the stomach wall, causing hemorrhage and attracting eosinophils. Inocula up to 300 larvae, however, did not cause peripheral hypereosinophilia. This species is the first ascaridoid which normally matures in fish that has been shown to penetrate the alimentary tract of a primate. Consequently, human consumption of raw seafood from at least the northern Gulf of Mexico free from infections, with Anisakis spp., Phocanema decipiens, or other species that mature in mammals or birds does not necessarily assure freedom from anisakiasis as previously assumed.

To determine the efficacy of atropine as an endoscopic premedication, we prospectively evaluated in double-blind fashion 196 elective endoscopies performed on 189 consecutive consenting patients. Group 1 (95 endoscopies) received meperidine, 1.5 mg/kg, intramuscularly 30 min prior to endoscopy. Group 2 (101 endoscopies) additionally received atropine, 0.6 mg, in the same injection. Endoscopy was performed by one of two investigators using a 13-mm fiberoptic instrument. Endoscopists and patients filled out postendoscopy questionnaires. Both endoscopists (p less than 0.01) and patients (p less than 0.05) noted less oral secretions after atropine. Endoscopists noted less gastric motility after atropine (p less than 0.05) and guessed correctly whether or not atropine had been given in two thirds of cases. They noted no overall difference, however, in the ease of the endoscopy (p greater than 0.05). Moreover, there were no differences in the patients' assessments of the acceptability of the procedure between the two groups (p greater than 0.05). We concluded that although atropine does not improve patients' tolerance for the examination or the endoscopists' ability to do an adequate examination, it does objectively decrease the amount of gastric motility and oral secretions. This latter effect could potentially decrease the hazard of aspiration, but such a benefit could not be demonstrated in our series.

Mouse-spleen lymphocytes, mouse mammary adenocarcinoma cells (MMA-67) and mouse lymphoma cells (S49.1) were radiolabeled with 111In and their in vivo migration patterns studied over a 24-72 h period after i.v. injection into syngeneic mice. All three cell lines showed different in vivo migration patterns. Initially, some trapping of the cells occurred in the lungs at 15 min. More MMA-67 cells were initially trapped in the lungs than S49.1 cells or lymphocytes. At 24 h, most of the 111In labeled cells had left the lungs and accumulated in various tissues and organs. At 48 and 72 h, only slight changes in the localization patterns of the 111In radiolabeled cells in vivo were noted when compared to the 24 h patterns. About 35% of the injected 111In was excreted from the animals over the 72 h period of these experiments. In vitro studies compared the growth and/or viability of 111In radiolabeled lymphocytes or tumor cells to nonradiolabeled lymphocytes or tumor cells. The percentage of 111In released from the cells in culture was also determined. Similar values for growth and/or viability were obtained between non-radiolabeled cells and MMA-67 cells radiolabeled with 1.35 dpm 111In per cell; S49.1 cells, 0.51 dpm111In per cell; and lymphocytes, 0.04 dpm 111In per cell.

There is relatively poor documentation of the effect of metoclopramide on the human esophageal body. We, therefore, studied several parameters of esophageal function in 19 normal volunteers both before and after 20 mg intravenous metoclopramide. Contraction amplitude, wave duration, velocity, and propagation time were increased after metoclopramide. These changes were more pronounced in the distal esophagus. At the most distal manometric recording level located 2 cm above the lower esophageal sphincter, contraction amplitude increased 39% (p less than 0.01) and duration increased 22.5% (p less than 0.01) after metoclopramide. We conclude that in normal subjects metoclopramide has an effect predominant in the distal body of the esophagus.